Feedback circuit, air conditioner, and feedback method

Abstract

To provide a feedback circuit capable of reducing power consumption in comparison with a feedback circuit which is driven by the same voltage as a voltage supplied to a load.SOLUTION: A feedback circuit is provided for a switching power supply. In the switching power supply, an input side and an output side are connected via one or more transformers, a switching circuit which executes a switching operation in a case where a first signal is received is provided at the input side, and a load is connected at the output side. The feedback circuit comprises a photocoupler which emits light, in a case where a first voltage supplied to the load is higher than a desired voltage, based on a second voltage lower than the first voltage and supplied from one transformer in the one or more transformers and outputs the first signal responding to the light emission to the switching circuit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a feedback circuit, an air conditioner, and a feedback method. [Background technology]

[0002] Switching power supplies are sometimes used in air conditioners and other appliances. In order to accurately output the desired voltage, switching power supplies may detect the voltage supplied to the load and feed the detection result back to the switching circuit on the input side. Patent Document 1 discloses a related technique for reducing current in an LED (Light Emitting Diode) lighting circuit. Patent Document 2 discloses a related technique relating to a short-circuit protection circuit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-002104 [Patent Document 2] Japanese Patent Application Publication No. 10-117477 Summary of the Invention [Problem to be solved by the invention]

[0004] Meanwhile, there is a demand for a technology that can reduce power consumption compared to a feedback circuit that is driven by the same voltage as the voltage supplied to the load.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a feedback circuit, an air conditioner, and a feedback method that can reduce power consumption compared to a feedback circuit that is driven by the same voltage as the voltage supplied to the load. [Means for solving the problem]

[0006] In order to solve the above problem, the feedback circuit according to the present disclosure comprises: A feedback circuit for a switching power supply, the switching power supply having an input side and an output side connected via one or more transformers, including a switching circuit on the input side that performs a switching operation when receiving a first signal, and a load connected to the output side, the feedback circuit including a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a shunt regulator, a capacitor, and a photocoupler, a first terminal of the first resistor being connected to a first terminal of the second resistor, a first terminal of the third resistor, and a first terminal of the shunt regulator, a second terminal of the second resistor being connected to a second terminal of the shunt regulator, a second terminal of the third resistor being connected to a first terminal of the capacitor, and a third terminal of the shunt regulator being connected to the second terminal of the capacitor, the first terminal of the fourth resistor, and a photocoupler. the second terminal of the fourth resistor is connected to the second terminal of the photocoupler and the first terminal of the fifth resistor; the second terminal of the first resistor is connected to the first terminal of the feedback circuit; the second terminal of the fifth resistor is connected to the second terminal of the feedback circuit; the second terminal of the second resistor is connected to the third terminal of the feedback circuit; the third terminal of the photocoupler is connected to the fourth terminal of the feedback circuit; and the fourth terminal of the photocoupler is connected to the fifth terminal of the feedback circuit; when a first voltage supplied to the load is higher than a desired voltage, the photocoupler emits light based on a second voltage supplied from one of the one or more transformers which is lower than the first voltage, and outputs the first signal corresponding to the light emission to the switching circuit. A feedback circuit according to the present disclosure is a feedback circuit for a switching power supply, the switching power supply having an input side and an output side connected via one or more transformers, the input side including a switching circuit that performs a switching operation when receiving a first signal, and the output side including a load, the feedback circuit including a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a shunt regulator, a capacitor, a photocoupler, and an NPN transistor, a first terminal of the first resistor is connected to a first terminal of the second resistor, a first terminal of the third resistor, and a first terminal of the shunt regulator, a second terminal of the second resistor is connected to a second terminal of the shunt regulator, a first terminal of the seventh resistor, and an emitter of the NPN transistor, a second terminal of the third resistor is connected to a first terminal of the capacitor, and a third terminal of the shunt regulator is connected to a second terminal of the capacitor, a first terminal of the fifth resistor, and a first terminal of the sixth resistor, and a first terminal of the photocoupler is connected to the NPN transistor. a second terminal of the photocoupler connected to the first terminal of the fourth resistor, a fourth terminal of the photocoupler connected to the first terminal of the eighth resistor, a second terminal of the fourth resistor connected to the second terminal of the fifth resistor, a second terminal of the sixth resistor connected to the second terminal of the seventh resistor and the base of the NPN transistor, a second terminal of the eighth resistor connected to the first terminal of the ninth resistor, a third terminal of the photocoupler connected to a power supply terminal to which a DC voltage is supplied, and a second terminal of the first resistor connected to the first terminal of the feedback circuit a second terminal of the fifth resistor connected to a second terminal of the feedback circuit, a second terminal of the second resistor connected to a third terminal of the feedback circuit, a second terminal of the ninth resistor connected to a fourth terminal of the feedback circuit, and a second terminal of the eighth resistor connected to a fifth terminal of the feedback circuit; and the photocoupler emits light based on a second voltage supplied from one of the one or more transformers that is lower than the first voltage when a first voltage supplied to the load is higher than a desired voltage;The first signal corresponding to light emission is output to the switching circuit. A feedback circuit according to the present disclosure is a feedback circuit for a switching power supply, the switching power supply having an input side and an output side connected via one or more transformers, the input side including a switching circuit that performs a switching operation when receiving a first signal, and the output side including a load, the feedback circuit including a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a shunt regulator, a capacitor, a photocoupler, and a PNP transistor, a first terminal of the first resistor is connected to a first terminal of the second resistor, a first terminal of the third resistor, and a first terminal of the shunt regulator, a second terminal of the second resistor is connected to a second terminal of the shunt regulator and a collector of the PNP transistor, a second terminal of the third resistor is connected to a first terminal of the capacitor, and a third terminal of the shunt regulator is connected to the second terminal of the capacitor, the first terminal of the fifth resistor, and a base of the PNP transistor, and a first terminal of the photocoupler is connected to the PNP transistor. the second terminal of the photocoupler is connected to the emitter of the one or more transformers, the second terminal of the photocoupler is connected to the first terminal of the fourth resistor, the fourth terminal of the photocoupler is connected to the first terminal of the sixth resistor, the second terminal of the fourth resistor is connected to the second terminal of the fifth resistor, the second terminal of the sixth resistor is connected to the first terminal of the seventh resistor, the third terminal of the photocoupler is connected to a power supply terminal to which a DC voltage is supplied, the second terminal of the first resistor is connected to the first terminal of the feedback circuit, the second terminal of the fifth resistor is connected to the second terminal of the feedback circuit, the second terminal of the second resistor is connected to the third terminal of the feedback circuit, the second terminal of the seventh resistor is connected to the fourth terminal of the feedback circuit, and the second terminal of the sixth resistor is connected to the fifth terminal of the feedback circuit; when a first voltage supplied to the load is higher than a desired voltage, the photocoupler emits light based on a second voltage supplied from one of the one or more transformers that is lower than the first voltage, and outputs the first signal corresponding to the light emission to the switching circuit.

[0007] An air conditioner according to the present disclosure includes the above feedback circuit and at least one of an electronic expansion valve and an actuator as the load.

[0008] The feedback method according to the present disclosure includes: The circuit comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a shunt regulator, a capacitor, and a photocoupler, wherein a first terminal of the first resistor is connected to a first terminal of the second resistor, a first terminal of the third resistor, and a first terminal of the shunt regulator, a second terminal of the second resistor is connected to a second terminal of the shunt regulator, a second terminal of the third resistor is connected to a first terminal of the capacitor, a third terminal of the shunt regulator is connected to a second terminal of the capacitor, a first terminal of the fourth resistor, and a first terminal of the photocoupler, a second terminal of the fourth resistor is connected to a second terminal of the photocoupler, and a first terminal of the fifth resistor, a second terminal of the first resistor is connected to a first terminal of a feedback circuit, a second terminal of the fifth resistor is connected to a second terminal of the feedback circuit, and the second terminal of the second resistor is connected to a , connected to a third terminal of the feedback circuit, the third terminal of the photocoupler is connected to a fourth terminal of the feedback circuit, and the fourth terminal of the photocoupler is connected to a fifth terminal of the feedback circuit; and a feedback method performed by the feedback circuit for a switching power supply, wherein the switching power supply has an input side and an output side connected via one or more transformers, and includes a switching circuit on the input side that performs a switching operation when a first signal is received, and a load is connected to the output side; when a first voltage supplied to the load is higher than a desired voltage, the photocoupler emits light based on a second voltage supplied from one of the one or more transformers that is lower than the first voltage, and outputs the first signal corresponding to the light emission to the switching circuit. A feedback method according to the present disclosure includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a shunt regulator, a capacitor, a photocoupler, and an NPN transistor, wherein a first terminal of the first resistor is connected to a first terminal of the second resistor, a first terminal of the third resistor, and a first terminal of the shunt regulator, and a second terminal of the second resistor is connected to a second terminal of the shunt regulator, a first terminal of the seventh resistor, and an emitter of the NPN transistor, a second terminal of the third resistor is connected to the first terminal of the capacitor, a third terminal of the shunt regulator is connected to the second terminal of the capacitor, the first terminal of the fifth resistor, and the first terminal of the sixth resistor, a first terminal of the photocoupler is connected to the collector of the NPN transistor, a second terminal of the photocoupler is connected to the first terminal of the fourth resistor, a fourth terminal of the photocoupler is connected to the first terminal of the eighth resistor, a second terminal of the fourth resistor is connected to the second terminal of the fifth resistor, and a second terminal of the sixth resistor is connected to the collector of the NPN transistor, a second terminal of the seventh resistor and a base of the NPN transistor, the second terminal of the eighth resistor is connected to the first terminal of the ninth resistor, a third terminal of the photocoupler is connected to a power supply terminal to which a DC voltage is supplied, the second terminal of the first resistor is connected to a first terminal of a feedback circuit, the second terminal of the fifth resistor is connected to the second terminal of the feedback circuit, the second terminal of the second resistor is connected to the third terminal of the feedback circuit, the second terminal of the ninth resistor is connected to a fourth terminal of the feedback circuit, and the second terminal of the eighth resistor is connected to a fifth terminal of the feedback circuit.The light emitting device emits light based on a second voltage supplied from one of the one or more transformers, the second voltage being lower than the first voltage, and outputs the first signal corresponding to the light emission to the switching circuit. A feedback method according to the present disclosure includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a shunt regulator, a capacitor, a photocoupler, and a PNP transistor, wherein a first terminal of the first resistor is connected to a first terminal of the second resistor, a first terminal of the third resistor, and a first terminal of the shunt regulator, a second terminal of the second resistor is connected to a second terminal of the shunt regulator and a collector of the PNP transistor, and a second terminal of the third resistor is connected to a first terminal of the capacitor. , a third terminal of the shunt regulator is connected to a second terminal of the capacitor, a first terminal of the fifth resistor, and a base of the PNP transistor, a first terminal of the photocoupler is connected to an emitter of the PNP transistor, a second terminal of the photocoupler is connected to a first terminal of the fourth resistor, a fourth terminal of the photocoupler is connected to a first terminal of the sixth resistor, a second terminal of the fourth resistor is connected to a second terminal of the fifth resistor, a second terminal of the sixth resistor is connected to a first terminal of the seventh resistor, and a third terminal of the photocoupler is connected to a second terminal of the fifth resistor. a terminal connected to a power supply terminal to which a DC voltage is supplied, a second terminal of the first resistor connected to a first terminal of a feedback circuit, a second terminal of the fifth resistor connected to a second terminal of the feedback circuit, a second terminal of the second resistor connected to a third terminal of the feedback circuit, a second terminal of the seventh resistor connected to a fourth terminal of the feedback circuit, and a second terminal of the sixth resistor connected to a fifth terminal of the feedback circuit; and a feedback method performed by the feedback circuit for a switching power supply, wherein the switching power supply has an input side and an output side connected via one or more transformers, and includes a switching circuit on the input side that performs a switching operation when a first signal is received, and a load is connected to the output side; and when a first voltage supplied to the load is higher than a desired voltage, the photocoupler emits light based on a second voltage supplied from one of the one or more transformers that is lower than the first voltage, and outputs the first signal corresponding to the light emission to the switching circuit. [Effects of the Invention]

[0009] According to the feedback circuit, air conditioner, and feedback method disclosed herein, it is possible to reduce power consumption compared to a feedback circuit that is driven by the same voltage as the voltage supplied to the load. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an example of the configuration of an air conditioner according to a first embodiment of the present disclosure. [Figure 2] FIG. 4 is a diagram illustrating an example of a processing flow of a feedback circuit according to the first embodiment of the present disclosure. [Figure 3] FIG. 4 is a diagram showing an example of the configuration of an air conditioner 1 according to a second embodiment of the present disclosure. [Figure 4] FIG. 10 is a diagram illustrating an example of a processing flow of a feedback circuit according to a second embodiment of the present disclosure. [Figure 5] FIG. 10 is a diagram showing an example of the configuration of an air conditioner 1 according to a third embodiment of the present disclosure. [Figure 6] FIG. 10 is a first diagram illustrating an example of a transformer according to a modified example of the first to third embodiments of the present disclosure. [Figure 7]FIG. 10 is a second diagram illustrating an example of a transformer according to a modified example of the first to third embodiments of the present disclosure. [Figure 8] FIG. 1 is a schematic block diagram illustrating the configuration of a computer according to at least one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] First Embodiment DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An air conditioner according to a first embodiment of the present disclosure will be described below with reference to the accompanying drawings.

[0012] (Air conditioner configuration) 1 is a diagram showing the configuration of an air conditioner 1 according to a first embodiment of the present disclosure. As shown in FIG. 1, the air conditioner 1 includes a switching power supply 2, a load 3, and a feedback circuit 4.

[0013] A first terminal of the switching power supply 2 is connected to a first terminal of the load 3 and a first terminal of the feedback circuit 4. A second terminal of the switching power supply 2 is connected to a second terminal of the feedback circuit 4. A third terminal of the switching power supply 2 is connected to the third terminal of the feedback circuit 4. A fourth terminal of the switching power supply 2 is connected to the fourth terminal of the feedback circuit 4. A fifth terminal of the switching power supply 2 is connected to the fifth terminal of the feedback circuit 4.

[0014] The switching power supply 2 includes an AC power supply 10, a rectifier circuit 20, a capacitor 30, a switching circuit 40, a transformer 50, and a diode 60. The transformer 50 includes a primary coil 50a and a secondary coil 50b. The diode 60 includes a diode 60a and a diode 60b.

[0015] An AC power supply 10 outputs an AC voltage to a rectifier circuit 20. The rectifier circuit 20 converts the AC voltage output by the AC power supply 10 into a DC voltage. The rectifier circuit 20 charges a capacitor 30 with the rectified DC voltage. The rectifier circuit 20 is, for example, a diode bridge circuit. The capacitor 30 smoothes the rectified DC voltage.

[0016] When receiving a first signal from the outside, the switching circuit 40 is turned on and performs a switching operation to pass a current. When not receiving the first signal from the outside, the switching circuit 40 is turned off and does not pass a current (stops switching). In other words, the switching circuit 40 adjusts the voltage generated in the primary coil 50a of the transformer 50 by PWM (Pulse Width Modulation) control based on the first signal. As a result, the voltage generated in the secondary coil 50b of the transformer 50 is adjusted to a desired voltage.

[0017] The secondary coil 50b includes a secondary coil 50b1 and a secondary coil 50b2. The secondary coil 50b1 is the high-potential coil of the secondary coil 50b. The secondary coil 50b2 is the low-potential coil of the secondary coil 50b.

[0018] Diode 60a supplies the voltage on the high potential side of secondary coil 50b1 to load 3. In this case, the voltage supplied to load 3 drops by the forward voltage of diode 60a relative to the voltage on the high potential side of secondary coil 50b1. Diode 60b supplies the voltage on the high potential side of secondary coil 50b2 to feedback circuit 4. In this case, the voltage supplied to feedback circuit 4 drops by the forward voltage of diode 60b relative to the voltage on the high potential side of secondary coil 50b2.

[0019] A first terminal of the AC power supply 10 is connected to a first terminal of the rectifier circuit 20. A second terminal of the AC power supply 10 is connected to a second terminal of the rectifier circuit 20. A third terminal of the rectifier circuit 20 is connected to a first terminal of the capacitor 30 and a first terminal of the primary coil 50a. A fourth terminal of the rectifier circuit 20 is connected to a second terminal of the capacitor 30, a first terminal of the switching circuit 40, and a fifth terminal of the switching power supply 2. A second terminal of the switching circuit 40 is connected to a second terminal of the primary coil 50a. A third terminal of the switching circuit 40 is connected to a fourth terminal of the switching power supply 2.

[0020] A first terminal of the secondary coil 50b is connected to the anode of the diode 60a. A second terminal of the secondary coil 50b is connected to the anode of the diode 60b. A third terminal of the secondary coil 50b is connected to the third terminal of the switching power supply 2. A cathode of the diode 60a is connected to the first terminal of the switching power supply 2. A cathode of the diode 60b is connected to the second terminal of the switching power supply 2.

[0021] The stage before the primary coil 50a (i.e., the AC power supply 10 side) is the input side of the switching power supply 2. The stage after the secondary coil 50b (i.e., the load 3 side) is the output side of the switching power supply 2. In other words, the input side and the output side are connected via the transformer 50.

[0022] The load 3 includes an actuator 70 and an electronic expansion valve 80. The actuator 70 operates various mechanisms. Examples of the actuator 70 include an actuator that moves blades to change the airflow direction, and an actuator that moves a suction nozzle or filter when automatically cleaning the filter. The electronic expansion valve 80 causes the refrigerant to flow in the air conditioner 1 at an opening degree according to control.

[0023] A first terminal of the actuator 70 and a first terminal of the electronic expansion valve 80 are connected to a first terminal of the load 3. Note that although the actuator 70 and the electronic expansion valve 80 are given here as specific examples of the load, the load is not limited to these. For example, the indoor unit does not have an electronic expansion valve 80. The load targeted in the embodiments of the present disclosure is a load that fluctuates greatly, such as the actuator 70 and the electronic expansion valve 80.

[0024] 1, the feedback circuit 4 includes a resistor 90, a resistor 100, a resistor 110, a shunt regulator 120, a capacitor 130, a resistor 140, a photocoupler 150, and a resistor 160. Note that although the photocoupler 150 is shown as two separate parts in FIG. 1, the actual photocoupler 150 is housed in a single package.

[0025] A first terminal of the resistor 90 is connected to a first terminal of the resistor 100, a first terminal of the resistor 110, and a first terminal of the shunt regulator 120. A second terminal of the resistor 90 is connected to a first terminal of the feedback circuit 4.

[0026] The second terminal of resistor 100 is connected to the second terminal of shunt regulator 120 and the third terminal of feedback circuit 4. The second terminal of resistor 110 is connected to the first terminal of capacitor 130. The third terminal of shunt regulator 120 is connected to the second terminal of capacitor 130, the first terminal of resistor 140, and the first terminal of photocoupler 150.

[0027] The second terminal of the resistor 140 is connected to the second terminal of the photocoupler 150 and the first terminal of the resistor 160. The third terminal of the photocoupler 150 is connected to the first terminal of the feedback circuit 4. 4 The fourth terminal of the photocoupler 150 is connected to the Feedback Circuit 4 The second terminal of the resistor 160 is connected to the second terminal of the feedback circuit 4.

[0028] When the first voltage supplied to the load 3 is higher than the desired voltage, the photocoupler 150 emits light based on a second voltage supplied from the transformer 50 that is lower than the first voltage, and outputs a first signal corresponding to the emission of light to the switching circuit 40.

[0029] The resistance values ​​of resistors 90 and 100 are determined so that when a voltage obtained by dividing the first voltage supplied to load 3 is higher than a predetermined voltage, shunt regulator 120 is turned on and current flows to the input element of photocoupler 150 via diode 60b and resistor 160. In other words, the resistance values ​​of resistors 90 and 100 are determined so that when the first voltage supplied to load 3 is higher than a desired voltage, shunt regulator 120 is turned on. Therefore, resistors 90, 100, and shunt regulator 120 are an example of a detection circuit that detects whether the first voltage supplied to load 3 is higher than the desired voltage. When a current flows through the input element of photocoupler 150, it emits light. When the input element of photocoupler 150 emits light, the output element of photocoupler 150 receives the light, causing a current to flow, and the voltage at the fourth terminal of feedback circuit 4 becomes a low-level voltage.

[0030] By supplying power from diode 60b to shunt regulator 120 via resistor 160 and resistor 140, a reference voltage for switching photocoupler 150 between the on state and the off state is generated within shunt regulator 120. The difference between the potential at the cathode of diode 60b and the potential at the cathode of shunt regulator 120 is applied to resistor 160 and the diode of photocoupler 150, and a current of a magnitude sufficient to cause photocoupler 150 to emit light must flow. The resistance value of resistor 160 is determined taking these factors into consideration. The resistance value of resistor 140 is determined so that a current of a magnitude sufficient to drive shunt regulator 120 flows. Resistor 110 and capacitor 130 are used for phase compensation to prevent oscillation of feedback circuit 4, and their values ​​are determined taking into account factors such as phase margin and gain margin.

[0031] (Feedback circuit operation) Next, the processing performed by the feedback circuit 4 will be described with reference to Fig. 2. Fig. 2 is a diagram showing an example of a processing flow of the feedback circuit 4 according to the first embodiment of the present disclosure. Note that the switching circuit 40 performs a switching operation (i.e., causes a current to flow through the transformer 50) when a high-level voltage is applied to the third terminal of the switching circuit 40, and stops the switching operation when a low-level voltage is applied to the third terminal of the switching circuit 40. Here, it is assumed that a high-level voltage is applied to the third terminal of the switching circuit 40.

[0032] The AC power supply 10 outputs an AC voltage to the rectifier circuit 20. The rectifier circuit 20 rectifies the AC voltage and outputs the resulting voltage to the capacitor 30. The capacitor 30 smoothes the rectified voltage. The transformer 50 outputs a voltage from its secondary side that corresponds to the voltage across the capacitor 30, depending on the number of windings in the primary coil 50a and the secondary coil 50b. The voltage output from the secondary side of the transformer 50 is supplied to the load 3 via a diode 60a as a first voltage. The voltage output from the secondary side of the transformer 50 is supplied to the feedback circuit 4 via a diode 60b as a second voltage, which is lower than the first voltage. The current supplied to the load 3 is, for example, a current of several amperes, which enables the load 3 to operate. The current supplied to the feedback circuit 4 is, for example, a current of several milliamperes, which enables the input element of the photocoupler 150 to emit light. That is, the current supplied to the feedback circuit 4 is negligibly small compared to the current supplied to the load 3 .

[0033] When the voltage obtained by dividing the first voltage supplied to the load 3 is higher than a predetermined voltage, the shunt regulator 120 is turned on, causing a current to flow to the input element of the photocoupler 150 via the diode 60b and the resistor 160 (step S1). When a current flows through the input element of the photocoupler 150, it emits light (step S2). When the input element of the photocoupler 150 emits light, the output element of the photocoupler 150 receives the light, causing a current to flow, and the voltage at the fourth terminal of the feedback circuit 4 becomes a low-level voltage. In other words, the third terminal of the switching circuit 40 becomes a low-level voltage (step S3). When the third terminal of the switching circuit 40 becomes a low-level voltage, the switching circuit 40 stops switching. When the switching circuit 40 stops switching, the voltage on the primary side of the transformer 50 drops, and accordingly, the voltage on the secondary side of the transformer 50 drops. When the voltage on the secondary side of the transformer 50 drops, the voltage supplied to the load 3 drops. When the voltage supplied to the load 3 decreases, the voltage obtained by dividing the first voltage supplied to the load 3 becomes lower than the predetermined voltage, and the shunt regulator 120 enters an OFF state. When the shunt regulator 120 enters an OFF state, no current flows through the input element of the photocoupler 150, and the voltage at the output of the shunt regulator 120 is maintained at a desired voltage at which the input element of the photocoupler 150 does not emit light, via the path of the diode 60b, the resistor 160, the resistor 140, the capacitor 130, the resistor 110, and the resistor 100. Because no current flows through the input element of the photocoupler 150 (step S4), the input element of the photocoupler 150 does not emit light (step S5), no current flows through the output element of the photocoupler 150, and the voltage at the fourth terminal of the feedback circuit 4 becomes a high-level voltage (step S6). In other words, the third terminal of the switching circuit 40 becomes a high-level voltage, and the switching circuit 40 performs a switching operation. In this way, the feedback circuit 4 detects the first voltage supplied to the load 3, and outputs a high-level voltage or a low-level voltage to the switching circuit 40.

[0034] (advantage) In the first embodiment, the feedback circuit 4 operates at a second voltage that is lower than a first voltage supplied to the load 3. Therefore, the feedback circuit 4 according to the first embodiment can reduce power consumption compared to a comparable feedback circuit that operates at the first voltage.

[0035] Second Embodiment An air conditioner according to a first embodiment of the present disclosure will be described.

[0036] (Air conditioner configuration) Fig. 3 is a diagram showing an example of the configuration of an air conditioner 1 according to a second embodiment of the present disclosure. As shown in Fig. 3, the air conditioner 1 includes a switching power supply 2, a load 3, and a feedback circuit 4. Here, the differences between the air conditioner 1 according to the second embodiment of the present disclosure and the air conditioner 1 according to the first embodiment of the present disclosure shown in Fig. 1 will be mainly described.

[0037] The difference between the air conditioner 1 according to the second embodiment of the present disclosure and the air conditioner 1 according to the first embodiment of the present disclosure is the configuration of the feedback circuit 4. The feedback circuit 4 according to the second embodiment of the present disclosure is a circuit that can further reduce power consumption compared to the feedback circuit 4 according to the first embodiment of the present disclosure.

[0038] 3, the feedback circuit 4 includes a resistor 90, a resistor 100, a resistor 110, a shunt regulator 120, a capacitor 130, a photocoupler 150, a resistor 160, a resistor 170, a resistor 180, a resistor 190, an NPN transistor 200, a resistor 210, and a resistor 220. Note that in FIG. 3, the photocoupler 150 is shown as two separate parts, as in FIG. 1, but the actual photocoupler 150 is housed in a single package.

[0039] A first terminal of the resistor 90 is connected to a first terminal of the resistor 100, a first terminal of the resistor 110, and a first terminal of the shunt regulator 120. A second terminal of the resistor 90 is connected to a first terminal of the feedback circuit 4.

[0040] The second terminal of resistor 100 is connected to the second terminal of shunt regulator 120, the first terminal of resistor 190, the emitter of NPN transistor 200, and the third terminal of feedback circuit 4. The second terminal of resistor 110 is connected to the first terminal of capacitor 130. The third terminal of shunt regulator 120 is connected to the second terminal of capacitor 130, the first terminal of resistor 170, and the first terminal of resistor 180.

[0041] The first terminal of the photocoupler 150 is connected to the collector of the NPN transistor 200. The second terminal of the photocoupler 150 is connected to the first terminal of the resistor 160. The third terminal of the photocoupler 150 is connected to a power supply terminal. This power supply terminal may be a terminal that outputs the DC voltage shown in FIG. 3 or a terminal through which a power supply (not shown) outputs a DC voltage, as long as it is a terminal that can supply a DC voltage that enables the desired operation. The fourth terminal of the photocoupler 150 is connected to the first terminal of the resistor 210. The second terminal of the resistor 160 is connected to the second terminal of the resistor 170 and the second terminal of the feedback circuit 4.

[0042] The second terminal of the resistor 180 is connected to the second terminal of the resistor 190 and the base of the NPN transistor 210. The second terminal of the resistor 210 is connected to the first terminal of the resistor 220 and the first terminal of the feedback circuit 4. 5 The second terminal of the resistor 220 is connected to the first terminal of the feedback circuit 4. 4 It is connected to the terminal.

[0043] The resistance value of resistor 170 is determined so that the operation of shunt regulator 120 can be maintained when shunt regulator 120 is operable. The current that can maintain the operation of shunt regulator 120 is, for example, about several hundred microamperes, which is smaller than the current, for example, about several milliamperes, required to light the input element of photocoupler 150. Therefore, the feedback circuit 4 according to the second embodiment of the present disclosure can further reduce power consumption compared to the feedback circuit 4 according to the first embodiment of the present disclosure.

[0044] The resistance values ​​of resistors 180 and 190 are determined so that when shunt regulator 120 is in the off state, NPN transistor 200 is in the on state, and when shunt regulator 120 is in the on state, NPN transistor 200 is in the off state.

[0045] (Feedback circuit operation) Next, the processing performed by the feedback circuit 4 will be described with reference to FIG. 4. FIG. 4 is a diagram illustrating an example of a processing flow of the feedback circuit 4 according to the second embodiment of the present disclosure. The switching circuit 40 performs a switching operation (i.e., causes a current to flow through the transformer 50) when a high-level voltage is applied to the third terminal of the switching circuit 40, and stops the switching operation when a low-level voltage is applied to the third terminal of the switching circuit 40. Here, it is assumed that a high-level voltage is applied to the third terminal of the switching circuit 40. Note that, similar to the processing flow illustrated in FIG. 2, the feedback circuit 4 detects a first voltage supplied to the load 3 and outputs a high-level voltage or a low-level voltage to the switching circuit 40. However, the light emission of the input element of the photocoupler 150 in response to the detection result of the first voltage is opposite to that in the first embodiment of the present disclosure. That is, when the first voltage is higher than the desired voltage, the input element of the photocoupler 150 does not emit light, and when the first voltage is lower than the desired voltage, the input element of the photocoupler 150 emits light.

[0046] The AC power supply 10 outputs an AC voltage to the rectifier circuit 20. The rectifier circuit 20 rectifies the AC voltage and outputs the resulting voltage to the capacitor 30. The capacitor 30 smoothes the rectified voltage. The transformer 50 outputs a voltage from its secondary side that corresponds to the voltage across the capacitor 30, depending on the number of windings in the primary coil 50a and the secondary coil 50b. The voltage output from the secondary side of the transformer 50 is supplied to the load 3 via a diode 60a as a first voltage. The voltage output from the secondary side of the transformer 50 is supplied to the feedback circuit 4 via a diode 60b as a second voltage, which is lower than the first voltage. The current supplied to the load 3 is, for example, a current of several amperes, which enables the load 3 to operate. The current supplied to the feedback circuit 4 is, for example, a current of several milliamperes, which enables the input element of the photocoupler 150 to emit light. That is, the current supplied to the feedback circuit 4 is negligibly small compared to the current supplied to the load 3 .

[0047] When the voltage obtained by dividing the first voltage supplied to the load 3 is higher than a predetermined voltage, the shunt regulator 120 is turned on, causing a current to flow through the resistor 170 and the path of the shunt regulator 120. In this case, no current flows through the resistors 180 and 190 large enough to turn on the NPN transistor 200. Therefore, the NPN transistor 200 is in an off state. When the NPN transistor 200 is in an off state, no current flows through the input element of the photocoupler 150 (step S11), and the photocoupler 150 does not emit light (step S12). As a result, no current flows through the output element of the photocoupler 150, and the voltage at the fourth terminal of the feedback circuit 4 becomes a low-level voltage (step S13). When the third terminal of the switching circuit 40 becomes a low-level voltage, the switching circuit 40 stops switching. When the switching circuit 40 stops switching, the voltage on the primary side of the transformer 50 drops, and accordingly, the voltage on the secondary side of the transformer 50 drops. When the voltage on the secondary side of transformer 50 decreases, the voltage supplied to load 3 decreases. When the voltage supplied to load 3 decreases, the voltage obtained by dividing the first voltage supplied to load 3 becomes lower than the predetermined voltage, shunt regulator 120 enters an OFF state, and no current flows through shunt regulator 120. When shunt regulator 120 enters an OFF state, current flows through the path of diode 60b, resistor 170, resistor 180, and resistor 190, and NPN transistor 200 enters an ON state. When NPN transistor 200 enters an ON state, current flows through the path of diode 60b, resistor 160, the input element of photocoupler 150, and NPN transistor 200 (step S14), and the input element of photocoupler 150 emits light (step S15). When the input element of photocoupler 150 emits light, a current flows through the output element of photocoupler 150, and a current also flows through resistors 210 and 220, causing the voltage at the fourth terminal of feedback circuit 4 to become a high-level voltage (step S16). That is, the third terminal of switching circuit 40 becomes a high-level voltage, and switching circuit 40 performs a switching operation. In this way, feedback circuit 4 detects the first voltage supplied to load 3, and outputs a high-level voltage or a low-level voltage to switching circuit 40.

[0048] (advantage) In the second embodiment, the feedback circuit 4 does not cause the input element of the photocoupler 150 to emit light when the first voltage is higher than the desired voltage, so that the current can be reduced to a level that maintains the operation of the shunt regulator 120, which is less than the current required to cause the input element of the photocoupler 150 to emit light, which was required in the first embodiment.

[0049] Third Embodiment An air conditioner according to a first embodiment of the present disclosure will be described.

[0050] (Air conditioner configuration) FIG. 5 is a diagram showing an example of the configuration of an air conditioner 1 according to a third embodiment of the present disclosure. As shown in FIG. 5, the air conditioner 1 includes a switching power supply 2, a load 3, and a feedback circuit 4. The air conditioner 1 according to the third embodiment of the present disclosure differs from the air conditioner 1 according to the second embodiment of the present disclosure in the configuration of the feedback circuit 4. The feedback circuit 4 according to the third embodiment of the present disclosure is obtained by replacing the resistor 180, the resistor 190, and the NPN transistor 200 in the feedback circuit 4 according to the second embodiment of the present disclosure with a PNP transistor 230. In this case, the first terminal of the resistor 180 may be replaced by the base of the PNP transistor 230, the collector of the NPN transistor 200 may be replaced by the emitter of the PNP transistor 230, and the emitter of the NPN transistor 200 may be replaced by the collector of the PNP transistor 230.

[0051] <Modifications of the First to Third Embodiments> 6 and 7 are diagrams showing examples of transformers according to modifications of the first to third embodiments. In the first to third embodiments, the air conditioner 1 has been described assuming that the transformer is one of transformers 50. However, in modifications of the first to third embodiments, as shown in FIGS. 6 and 7, the first voltage supplied to the load 3 and the second voltage supplied to the feedback circuit 4 may be realized using one or more transformers having multiple secondary coils.

[0052] The order of the processes in the embodiments of the present disclosure may be changed as long as the processes are performed appropriately.

[0053] The memory units and storage devices (including registers and latches) in the embodiments of the present disclosure may be provided anywhere within the range where appropriate information can be transmitted and received. Furthermore, there may be multiple memory units and storage devices, each of which stores data in a distributed manner, within the range where appropriate information can be transmitted and received.

[0054] Although the embodiments of the present disclosure have been described, the air conditioner 1 and other control devices may have a computer system built therein. The above-described processing steps are stored in the form of a program on a computer-readable recording medium, and the computer reads and executes this program to perform the above processing. Specific examples of computers are shown below. FIG. 8 is a schematic block diagram illustrating the configuration of a computer according to at least one embodiment. As shown in FIG. 8, the computer 5 includes a CPU 6, a main memory 7, a storage 8, and an interface 9. For example, the air conditioner 1 and other control devices described above are each implemented in a computer 5. The operations of each of the processing units described above are stored in the form of a program in storage 8. CPU 6 reads the program from storage 8, loads it into main memory 7, and executes the above processing in accordance with the program. CPU 6 also allocates storage areas in main memory 7 corresponding to each of the storage units described above in accordance with the program.

[0055] Examples of storage 8 include a hard disk drive (HDD), a solid state drive (SSD), a magnetic disk, a magneto-optical disk, a compact disc read-only memory (CD-ROM), a digital versatile disc read-only memory (DVD-ROM), and a semiconductor memory. Storage 8 may be an internal medium directly connected to the bus of computer 5, or an external medium connected to computer 5 via interface 9 or a communication line. In addition, when this program is distributed to computer 5 via a communication line, computer 5 that receives the program may load the program into main memory 7 and execute the above-mentioned processing. In at least one embodiment, storage 8 is a non-transitory tangible storage medium.

[0056] The program may also implement some of the functions described above. Furthermore, the program may be a file that can implement the functions described above in combination with a program already recorded in the computer system, a so-called differential file (differential program).

[0057] Although several embodiments of the present disclosure have been described, these embodiments are merely examples and do not limit the scope of the disclosure. Various additions, omissions, substitutions, and modifications may be made to these embodiments without departing from the spirit of the disclosure.

[0058] <Additional Notes> The feedback circuit, the air conditioner, and the feedback method described in each embodiment of the present disclosure can be understood, for example, as follows.

[0059] (1) The feedback circuit (4) according to the first aspect comprises: A feedback circuit for a switching power supply (2), comprising: The switching power supply (2) an input side and an output side are connected via one or more transformers (50), a switching circuit (40) is provided on the input side that performs a switching operation when a first signal is received, and a load (3) is connected to the output side; The feedback circuit (4) 、 before a photocoupler (150) that, when a first voltage supplied to the load (3) is higher than a desired voltage, emits light based on a second voltage supplied from one of the one or more transformers (50) that is lower than the first voltage, and outputs the first signal corresponding to the light emission to the switching circuit (40); Equipped with.

[0060] This allows the feedback circuit (4) to consume less power than a feedback circuit that is driven by the same voltage as the voltage supplied to the load.

[0061] (2) A feedback circuit (4) according to a second aspect is the feedback circuit (4) of (1), The transformer (50) is one, The photocoupler (150) 、 before When a first voltage supplied to the load (3) is higher than a desired voltage, the light source may emit light based on a second voltage supplied from a single transformer that is lower than the first voltage, and output the first signal corresponding to the light emission to the switching circuit (40).

[0062] This allows the feedback circuit (4) to be realized using one transformer.

[0063] (3) A feedback circuit (4) according to a third aspect is the feedback circuit (4) of (1), There are a plurality of the transformers (50), The photocoupler 、 before When a first voltage supplied to the load (3) is higher than a desired voltage, the light source may emit light based on a second voltage supplied from one of a plurality of transformers (50) that is lower than the first voltage, and output the first signal corresponding to the light emission to the switching circuit (40).

[0064] This allows the feedback circuit (4) to be realized using multiple transformers.

[0065] (4) A feedback circuit (4) according to a fourth aspect is any one of the feedback circuits (4) of (1) to (3), The number of turns at the position of the coil in the transformer (50) that outputs the first voltage is The number of turns may be greater than the number of turns at the position of the coil in the transformer (50) that outputs the second voltage.

[0066] This allows the feedback circuit (4) to realize a first voltage and a second voltage lower than the first voltage by changing the number of turns of the coil in the transformer (50).

[0067] (5) A feedback circuit (4) according to a fifth aspect is any one of the feedback circuits (4) of (1) to (4), The number of turns at the position of the transformer (50) that outputs the second voltage is The number of turns may be within a predetermined range that allows the photocoupler (150) to operate stably.

[0068] This allows the feedback circuit (4) to operate reliably.

[0069] (6) A feedback circuit (4) according to a sixth aspect is any one of the feedback circuits (4) of (1) to (5), a detection circuit (90, 100, 120) for detecting whether the first voltage is higher than the desired voltage; Equipped with The photocoupler (150) The light source may emit light based on the detection result of the detection circuit (90, 100, 120), and output the first signal corresponding to the emitted light to the switching circuit (40).

[0070] This allows the feedback circuit (4) to detect the first voltage. (7) A feedback circuit (4) according to a seventh aspect is the feedback circuit (4) of (6), The detection circuit (90, 100, 120) Whether or not the first voltage is higher than the desired voltage may be detected based on the first voltage output from the transformer (50).

[0071] As a result, the feedback circuit (4) can detect the first voltage with higher accuracy because the first voltage is detected based on a physical quantity derived from the first voltage.

[0072] (8) An air conditioner (1) according to an eighth aspect is A feedback circuit (4) according to any one of the first to seventh aspects; the load (3) being at least one of an electronic expansion valve (80) and an actuator (70); Equipped with.

[0073] This allows the air conditioner (1) to consume less power than the feedback circuit (4) that is driven by the same voltage as that supplied to the load (3).

[0074] (9) A feedback method according to a ninth aspect includes: A feedback method implemented by a feedback circuit (4) for a switching power supply, comprising: The switching power supply (2) an input side and an output side are connected via one or more transformers (50), a switching circuit (40) is provided on the input side that performs a switching operation when a first signal is received, and a load (3) is connected to the output side; The feedback circuit (4) 、 before When a first voltage supplied to the load (3) is higher than a desired voltage, the light emits light based on a second voltage supplied from one of the one or more transformers (50), the second voltage being lower than the first voltage, and the first signal corresponding to the light emission is output to the switching circuit (40).

[0075] This allows the feedback method to reduce power consumption compared to a feedback circuit that is driven by the same voltage as the voltage supplied to the load. [Explanation of symbols]

[0076] 1. Air conditioner 2. Switching power supply 3. Load 4. Feedback circuit 5. Computer 6 CPU 7. Main memory 8. Storage 9. Interface 10...AC power supply 20... Rectifier circuit 30, 130... Capacitor 40. Switching circuit 50...transformer 50a Primary coil 50b Secondary coil 60, 60a, 60b... diodes 70 Actuator 80 Electronic Expansion Valve 90, 100, 110, 140, 160, 170, 180, 190, 210, 220... Resistor 120···Shunt regulator 150···Photocoupler 200 NPN transistor 230 PNP transistor

Claims

1. 1. A feedback circuit for a switching power supply, comprising: The switching power supply an input side and an output side are connected via one or more transformers, a switching circuit that performs a switching operation when a first signal is received is provided on the input side, and a load is connected to the output side; The feedback circuit comprises: The circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a shunt regulator, a capacitor, and a photocoupler, wherein a first terminal of the first resistor is connected to a first terminal of the second resistor, a first terminal of the third resistor, and a first terminal of the shunt regulator, a second terminal of the second resistor is connected to a second terminal of the shunt regulator, a second terminal of the third resistor is connected to a first terminal of the capacitor, and a third terminal of the shunt regulator is connected to the second terminal of the capacitor, the first terminal of the fourth resistor, and the photocoupler. a first terminal of the fourth resistor connected to a second terminal of the photocoupler and a first terminal of the fifth resistor, a second terminal of the first resistor connected to a first terminal of the feedback circuit, a second terminal of the fifth resistor connected to a second terminal of the feedback circuit, the second terminal of the second resistor connected to a third terminal of the feedback circuit, the third terminal of the photocoupler connected to a fourth terminal of the feedback circuit, and the fourth terminal of the photocoupler connected to a fifth terminal of the feedback circuit; The photocoupler is When a first voltage supplied to the load is higher than a desired voltage, the light emitting device emits light based on a second voltage supplied from one of the one or more transformers, the second voltage being lower than the first voltage, and outputs the first signal corresponding to the light emission to the switching circuit. Feedback circuit.

2. A feedback circuit for a switching power supply, comprising: The switching power supply an input side and an output side are connected via one or more transformers, a switching circuit that performs a switching operation when a first signal is received is provided on the input side, and a load is connected to the output side; The feedback circuit comprises: a first terminal of the first resistor connected to the first terminal of the second resistor, the first terminal of the third resistor, and the first terminal of the shunt regulator; a second terminal of the second resistor connected to the second terminal of the shunt regulator, the first terminal of the seventh resistor, and the emitter of the NPN transistor; a second terminal of the third resistor connected to the first terminal of the capacitor; a third terminal of the shunt regulator connected to the second terminal of the capacitor, the first terminal of the fifth resistor, and the first terminal of the sixth resistor; a first terminal of the photocoupler connected to the collector of the NPN transistor; a first terminal of the NPN transistor connected to a first terminal of the feedback circuit; a fourth terminal of the photocoupler connected to a first terminal of the eighth resistor; a second terminal of the fourth resistor connected to a second terminal of the fifth resistor; a second terminal of the sixth resistor connected to a second terminal of the seventh resistor and to a base of the NPN transistor; a second terminal of the eighth resistor connected to a first terminal of the ninth resistor; a third terminal of the photocoupler connected to a power supply terminal to which a DC voltage is supplied; a second terminal of the first resistor connected to a first terminal of the feedback circuit; a second terminal of the fifth resistor connected to a second terminal of the feedback circuit; the second terminal of the second resistor connected to a third terminal of the feedback circuit; a second terminal of the ninth resistor connected to a fourth terminal of the feedback circuit; and a second terminal of the eighth resistor connected to a fifth terminal of the feedback circuit; The photocoupler is When a first voltage supplied to the load is higher than a desired voltage, the light emitting device emits light based on a second voltage supplied from one of the one or more transformers, the second voltage being lower than the first voltage, and outputs the first signal corresponding to the light emission to the switching circuit. Feedback circuit.

3. A feedback circuit for a switching power supply, comprising: The switching power supply an input side and an output side are connected via one or more transformers, a switching circuit that performs a switching operation when a first signal is received is provided on the input side, and a load is connected to the output side; The feedback circuit comprises: The circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a shunt regulator, a capacitor, a photocoupler, and a PNP transistor, wherein a first terminal of the first resistor is connected to a first terminal of the second resistor, a first terminal of the third resistor, and a first terminal of the shunt regulator, a second terminal of the second resistor is connected to a second terminal of the shunt regulator and a collector of the PNP transistor, a second terminal of the third resistor is connected to a first terminal of the capacitor, a third terminal of the shunt regulator is connected to the second terminal of the capacitor, the first terminal of the fifth resistor, and a base of the PNP transistor, a first terminal of the photocoupler is connected to the emitter of the PNP transistor, and a second terminal of the photocoupler is connected to the first terminal of the fourth resistor, a fourth terminal of the photocoupler is connected to the first terminal of the sixth resistor, a second terminal of the fourth resistor is connected to the second terminal of the fifth resistor, a second terminal of the sixth resistor is connected to the first terminal of the seventh resistor, a third terminal of the photocoupler is connected to a power supply terminal to which a DC voltage is supplied, a second terminal of the first resistor is connected to the first terminal of the feedback circuit, a second terminal of the fifth resistor is connected to the second terminal of the feedback circuit, the second terminal of the second resistor is connected to the third terminal of the feedback circuit, a second terminal of the seventh resistor is connected to the fourth terminal of the feedback circuit, and the second terminal of the sixth resistor is connected to the fifth terminal of the feedback circuit; The photocoupler is When a first voltage supplied to the load is higher than a desired voltage, the light emitting device emits light based on a second voltage supplied from one of the one or more transformers, the second voltage being lower than the first voltage, and outputs the first signal corresponding to the light emission to the switching circuit. Feedback circuit.

4. the number of the transformers is one, The photocoupler is When a first voltage supplied to the load is higher than a desired voltage, the light emits light based on a second voltage supplied from one transformer that is lower than the first voltage, and outputs the first signal corresponding to the light emission to the switching circuit. A feedback circuit according to any one of claims 1 to 3.

5. There are a plurality of the transformers, The photocoupler is When a first voltage supplied to the load is higher than a desired voltage, the light source emits light based on a second voltage supplied from one of a plurality of transformers, the second voltage being lower than the first voltage, and outputs the first signal corresponding to the light emission to the switching circuit. A feedback circuit according to any one of claims 1 to 3.

6. The number of turns at the position of the coil in the transformer that outputs the first voltage is the number of turns is greater than the number of turns at the position of the coil in the transformer that outputs the second voltage, A feedback circuit according to any one of claims 1 to 5.

7. The number of turns at the position of the transformer that outputs the second voltage is The number of turns is within a predetermined range in which the photocoupler operates stably. A feedback circuit according to any one of claims 1 to 6.

8. a detection circuit that detects whether the first voltage is greater than the desired voltage; Equipped with The photocoupler is a first signal corresponding to the emitted light is output to the switching circuit; A feedback circuit according to any one of claims 1 to 7.

9. The detection circuit detecting whether the first voltage is higher than the desired voltage based on a first voltage output by the transformer; 9. The feedback circuit of claim 8.

10. A feedback circuit according to any one of claims 1 to 9; the load being at least one of an electronic expansion valve and an actuator; An air conditioner equipped with:

11. A circuit comprising a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a shunt regulator, a capacitor, and a photocoupler, wherein a first terminal of the first resistor is connected to a first terminal of the second resistor, a first terminal of the third resistor, and a first terminal of the shunt regulator, a second terminal of the second resistor is connected to a second terminal of the shunt regulator, a second terminal of the third resistor is connected to a first terminal of the capacitor, a third terminal of the shunt regulator is connected to a second terminal of the capacitor, a first terminal of the fourth resistor, and a first terminal of the photocoupler, and a second terminal of the fourth resistor is connected to the photocoupler. a second terminal of the photocoupler connected to a first terminal of a feedback circuit, a second terminal of the fifth resistor connected to a second terminal of the feedback circuit, a third terminal of the second resistor connected to a third terminal of the feedback circuit, a fourth terminal of the feedback circuit, and a fifth terminal of the photocoupler connected to a fifth terminal of the feedback circuit, The switching power supply an input side and an output side are connected via one or more transformers, a switching circuit that performs a switching operation when a first signal is received is provided on the input side, and a load is connected to the output side; The photocoupler is When a first voltage supplied to the load is higher than a desired voltage, the light emitting device emits light based on a second voltage supplied from one of the one or more transformers, the second voltage being lower than the first voltage, and outputs the first signal corresponding to the light emission to the switching circuit. Feedback methods.

12. A circuit comprising a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a shunt regulator, a capacitor, a photocoupler, and an NPN transistor, wherein a first terminal of the first resistor is connected to a first terminal of the second resistor, a first terminal of the third resistor, and a first terminal of the shunt regulator, a second terminal of the second resistor is connected to a second terminal of the shunt regulator, a first terminal of the seventh resistor, and an emitter of the NPN transistor, a second terminal of the third resistor is connected to a first terminal of the capacitor, a third terminal of the shunt regulator is connected to a second terminal of the capacitor, a first terminal of the fifth resistor, and a first terminal of the sixth resistor, a first terminal of the photocoupler is connected to a collector of the NPN transistor, a second terminal of the photocoupler is connected to a first terminal of the fourth resistor, and a fourth terminal of the photocoupler is a first terminal of the photocoupler connected to a first terminal of the eighth resistor, a second terminal of the fourth resistor connected to a second terminal of the fifth resistor, a second terminal of the sixth resistor connected to a second terminal of the seventh resistor and a base of the NPN transistor, a second terminal of the eighth resistor connected to a first terminal of the ninth resistor, a third terminal of the photocoupler connected to a power supply terminal to which a DC voltage is supplied, a second terminal of the first resistor connected to a first terminal of a feedback circuit, a second terminal of the fifth resistor connected to a second terminal of the feedback circuit, the second terminal of the second resistor connected to a third terminal of the feedback circuit, a second terminal of the ninth resistor connected to a fourth terminal of the feedback circuit, and the second terminal of the eighth resistor connected to a fifth terminal of the feedback circuit, The switching power supply an input side and an output side are connected via one or more transformers, a switching circuit that performs a switching operation when a first signal is received is provided on the input side, and a load is connected to the output side; The photocoupler is When a first voltage supplied to the load is higher than a desired voltage, the light emitting device emits light based on a second voltage supplied from one of the one or more transformers, the second voltage being lower than the first voltage, and outputs the first signal corresponding to the light emission to the switching circuit. Feedback methods.

13. A circuit comprising a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a shunt regulator, a capacitor, a photocoupler, and a PNP transistor, wherein a first terminal of the first resistor is connected to a first terminal of the second resistor, a first terminal of the third resistor, and a first terminal of the shunt regulator, a second terminal of the second resistor is connected to a second terminal of the shunt regulator and a collector of the PNP transistor, a second terminal of the third resistor is connected to a first terminal of the capacitor, a third terminal of the shunt regulator is connected to a second terminal of the capacitor, a first terminal of the fifth resistor, and a base of the PNP transistor, a first terminal of the photocoupler is connected to an emitter of the PNP transistor, and a second terminal of the photocoupler is connected to a first terminal of the fourth resistor. a fourth terminal of the photocoupler is connected to a first terminal of the sixth resistor, a second terminal of the fourth resistor is connected to a second terminal of the fifth resistor, a second terminal of the sixth resistor is connected to a first terminal of the seventh resistor, a third terminal of the photocoupler is connected to a power supply terminal to which a DC voltage is supplied, a second terminal of the first resistor is connected to a first terminal of a feedback circuit, a second terminal of the fifth resistor is connected to a second terminal of the feedback circuit, the second terminal of the second resistor is connected to a third terminal of the feedback circuit, a second terminal of the seventh resistor is connected to a fourth terminal of the feedback circuit, and the second terminal of the sixth resistor is connected to a fifth terminal of the feedback circuit, The switching power supply an input side and an output side are connected via one or more transformers, a switching circuit that performs a switching operation when a first signal is received is provided on the input side, and a load is connected to the output side; The photocoupler is When a first voltage supplied to the load is higher than a desired voltage, the light emitting device emits light based on a second voltage supplied from one of the one or more transformers, the second voltage being lower than the first voltage, and outputs the first signal corresponding to the light emission to the switching circuit. Feedback methods.

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